<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <title>Page Title</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" type="text/css" media="screen" href="main.css" />
    <script src="main.js"></script>
    <style>
    * {
        margin: 0px;
        padding: 0px;
    }
    div {
        margin: 15px 15px;
        width: 350px;
        height: 180px;
        border: 1px solid black;
        border-radius: 7px;
        background:linear-gradient(red, yellow)
    }
    </style>
</head>
<body>
    <div></div>
</body>
</html>